A manometer is also called pressure meter or pressure gauge. Currently, conventional manometers can be roughly classified into two categories as electronic type and mechanical type. The electronic manometer typically integrates a pressure sensor and related electronic components to measure and display pressure value measured for example as Taiwan (ROC) patent application in number of TW093124608. Most mechanical manometers are adapted from Bourdon gauge, which basically integrates a Bourdon tube, a pivot with a pivot pin, a lever, a sector gear with gear train, an indicator needle and a hair spring to measure and display pressure value measured for example as Taiwan (ROC) patent application in number of TW088203528. Other mechanical manometers are adapted from diaphragm gauge, which basically integrates a diaphragm, a sliding shaft, sliding cylinder, a helical wire, a spring and an indicator needle to measure and display pressure value measured for example as Taiwan (ROC) patent application in number of TW6510501. However, there are some drawbacks in foregoing conventional manometers. Firstly, for displaying pressure value measured, both of the electronic manometer and mechanical manometer involve too many components with complicated structure. Secondly, for air pressure in the manometer, there is no protective means to keep it in safety range.
Having realized and addressed drawbacks aforesaid for conventional manometers, the applicant of the present invention works out a simple contrivance of the present invention to solve all the drawbacks aforesaid.